RFID Reader Time-Slot Scheduling to Reduce Tag Collisions
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Solution Overview
Problem
RFID tag readers face challenges in distinguishing between overlapping radio signals from multiple tags, leading to transmission collisions and reduced reading efficiency in congested environments.
Innovation Solution
Implementing a method where RFID tags are initialized with a range of time slots, designating a sub-range as quiescent slots during which they refrain from transmitting, and using a random number generator to select transmission slots, thereby reducing collisions and allowing readers to offload data during non-quiescent slots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If RFID tags transmit information simultaneously in a congested environment, then the reading speed may be fast, but transmission collisions occur and reading efficiency deteriorates
Solution Approach 1:
The patent segments the transmission time into multiple time slots, dividing the congested transmission environment into discrete temporal segments. Each RFID tag is assigned to transmit in a specific time slot, preventing simultaneous transmissions and eliminating collisions while maintaining reading speed through structured parallel processing.
Solution Approach 2:
The patent implements periodic transmission cycles where RFID tags transmit information in scheduled time slots rather than continuously or simultaneously. This periodic structure allows the reader to systematically query and receive data from multiple tags in sequence, ensuring reliable reception while maintaining overall reading efficiency.
2Quantity of substance
If all time slots are used for RFID tag transmissions, then data collection is maximized, but reader memory burden increases and data processing is delayed
Solution Approach 1:
The patent segments the time slots into two distinct categories: active transmission time slots for receiving RFID tag data and quiescent time slots for data processing and offloading. This temporal segmentation allows the reader to collect data during active slots and process/offload data during quiescent slots, preventing memory overflow and reducing processing delays.
Solution Approach 2:
The patent performs data offloading during quiescent time slots before the next data collection cycle begins. This preliminary action of clearing processed data from memory prevents accumulation and reduces the memory burden for subsequent cycles, enabling sustained high-volume data collection without increasing overall system complexity.
3Device complexity
If RFID tags transmit in overlapping time slots, then the system structure is simple, but signal interference occurs and reading accuracy deteriorates
Solution Approach 1:
The patent segments the transmission timeline into non-overlapping time slots, creating a simple yet effective structure where each RFID tag transmits in its designated slot. This segmentation eliminates signal interference by ensuring no two tags transmit simultaneously, thereby maintaining high reading accuracy without requiring complex interference mitigation techniques.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes transmission collisions, reduces memory burden on readers, and enables timely data processing by allowing partial data offloading and inter-reader communication to correct errors, enhancing reading efficiency in RFID systems.
Implementation Method 1
Radio frequency identity (RFID) tags are passive semiconductor devices that may be affixed to various items for conducting electronic scans and inventory control functions. The RFID tags typically do not have self-contained electric power sources and harvest electrical power from ambient radio frequency fields.
Data Source
AI summary
A radio frequency identity (RFID) tag reader. The reader comprises a radio transceiver; a non-transitory memory; a processor coupled to the radio transceiver and to the non-transitory memory; and an RFID tag reader application stored in the non-transitory memory. When executed by the processor, the application sends a message via the radio transceiver to a plurality of RFID tags indicating a first range of transmission time slots and indicating a second range of quiescent transmission time slots disposed within the range of transmission time slots, receives messages via the radio transceiver from the plurality of RFID tags during time slots that are outside the sub-range of quiescent transmission time slots, wherein the messages comprise information associated with items to which the plurality of RFID tags are affixed to, and transmits the information received from the plurality of RFID tags during the quiescent time slots.